1,3-dipole
Dipolar compound with electron delocalization and charge separation over 3 atoms
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In organic chemistry, a 1,3-dipolar compound or 1,3-dipole is a dipolar compound with delocalized electrons and a separation of charge over three atoms, as follows: the dipole has at least one resonance structure with positive and negative charges having a 1,3 relationship which can generally be denoted as +aâbâcâ, where a may be a carbon, oxygen or nitrogen, b may be nitrogen or oxygen, and c may be a carbon, oxygen or nitrogen.[1]

| From top to bottom, azides, nitrones, and nitro compounds are examples of 1,3-dipoles. |
They are reactants in 1,3-dipolar cycloadditions.[2][3]
Known 1,3-dipoles are:
- Azides (RN3)
- Ozone (O3)
- Nitro compounds (RNO2)
- Diazo compounds (R2CN2)
- Some oxides
- Azoxide compounds (RN(O)NR)
- Carbonyl oxides (Criegee zwitterions)[4][5]
- Nitrile oxides (RCNâO)
- Nitrous oxide (N2O)
- Nitrones (R2CN(R)O)

- Some imines:
- Azomethine imine
- Nitrilimines (RCNâNR, analogous to nitrile oxide)
- Carbonyl imines
- Some ylides
- Azomethine ylide
- Nitrile ylide (RCNCR'2)
- Carbonyl ylide
- Thiosulfines (R2CSS)